EDITOR'S NOTE: Orlando's mayor on Monday revised the death toll in the nightclub shooting to 49, from 50. The 50th body was identified as gunman Omar Mateen.

The FBI said Sunday that the suspect in the Orlando nightclub shooting was investigated twice by the agency in recent years for connections to Islamic terror -- including a 2014 probe for possible ties to American suicide bomber Moner Mohammad Abu-Salha.

FBI agent Ron Hopper identified the suspect as Omar Mir Sadiq Mateen, 29, of Port St. Lucie, Fla.

Mateen early Sunday morning killed 50 and wounded 53 others inside the gay nightclub Pulse. He later died in a shootout with police after holding dozens of hostages for several hours.

Hopper told reporters at a press conference in Orlando that the FBI first became aware of Mateen in 2013, after he made inflammatory comments to coworkers alleging possible terrorist ties.

He said the agency thoroughly investigated the matter -- including conducting surveillance, checking records and interviewing Mateen and witnesses.

However, the case was closed because agents could not verify the “substance” of Mateen’s claims, Hopper said.  

Mateen is a U.S. citizen and a Muslim born in New York to parents from Afghanistan, according to authorities.

The FBI investigated Mateen again in 2014 for possible ties to Abu-Salha, a fellow Floridian, but concluded the two had minimal contact and that Mateen posed no terror “threat” at that time.

Hopper said Mateen was not under surveillance or being investigated at the time of the nightclub attack.

Mateen called 911 before the attack and pledged his allegiance to Islamic State terror group leader Abu Bakr al-Baghdadi, Fox News reported.

He also purportedly mentioned during the call the Tsarnaev brothers, who set off bombs at the 2013 Boston Marathon and were inspired by Islamic extremism.

Hopper did not confirmed such a call and said only that investigators are looking into “any and all connections both domestic and international terrorism.”

He also said the FBI is not “actively” looking for a second suspect or investigating any additional, related terror threats.

An agent for the Bureau of Alcohol, Tobacco, Firearms and Explosives said at the press conference that Mateen legally bought at least two firearms -- a handgun and a long gun -- within the past couple of weeks.

However, the agent declined to discuss specifics of the purchases.

Earlier in the day, top Capitol Hill lawmakers suggested Mateen appeared to have links to radical Islamic terrorism and that the FBI was aware of him and his activities.

Sen. Bill Nelson, D-Fla., said the FBI had told him that Mateen “appeared” to be connected to Islamic radicalism.

He also said the Senate’s intelligence staff thought that Mateen, married in 2009 to a woman who was born in Uzbekistan, had “some connection” to the Islamic State terror group.

California Democratic Rep. Adam Schiff said that local law enforcement said Mateen declared his allegiance to ISIS, which “indicates an ISIS-inspired act of terrorism.”

Schiff, a member of the House Permanent Select Committee on Intelligence, said other facts that suggest an Islamic extremist attack include the shooting taking place during Ramadan and ISIS leadership in Raqqa recently urging attacks this time of year.

New York GOP Rep. Pete King, a member of the House Homeland Security Committee, told Fox News that Mateen was “trained in weapons.”

“I don't want to release it before they do, but I can understand why the FBI was so quick to say this morning that they thought this had ISIS connections or at least ISIS ideology,” King said.